Multiple-TRX pico base station for providing improved wireless capacity and coverage in a building

ABSTRACT

One embodiment is directed to a system for providing wireless coverage and capacity for a public land mobile network within a building. The system comprises a pico base station comprising multiple transceiver units. The pico base station is installed in the building. The system further comprises a plurality of antennas located within the building. The plurality of antennas are located remotely from the pico base station. The pico base station is communicatively coupled to the public land mobile network. The pico base station is communicatively coupled to the plurality of antennas.

CROSS-REFERENCE TO RELATED APPLICATION

This Reissue Application is a reissue of U.S. patent application Ser.No. 12/367,449, filed Feb. 6, 2009, which issued as U.S. Pat. No.8,548,526. This application claims the benefit of U.S. ProvisionalPatent Application Ser. No. 61/027,363, filed on Feb. 8, 2008, which ishereby incorporated herein by reference.

This application is related to the following patent applications:

U.S. patent application Ser. No. 12/367,451, filed on even dateherewith, entitled “AN ENTERPRISE MOBILE NETWORK FOR PROVIDING CELLULARWIRELESS SERVICE USING LICENSED RADIO FREQUENCY SPECTRUM AND INTERNETPROTOCOL BACKHAUL”, which is hereby incorporated herein by reference;

U.S. patent application Ser. No. 12/367,454, filed on even dateherewith, entitled “AN ENTERPRISE MOBILE NETWORK FOR PROVIDING CELLULARWIRELESS SERVICE USING LICENSED RADIO FREQUENCY SPECTRUM AND SUPPORTINGMULTIPLE-DEVICE RING FOR INCOMING CALLS”, which is hereby incorporatedherein by reference; and

U.S. patent application Ser. No. 12/367,458, filed on even dateherewith, entitled “AN ENTERPRISE MOBILE NETWORK FOR PROVIDING CELLULARWIRELESS SERVICE USING LICENSED RADIO FREQUENCY SPECTRUM AND THE SESSIONINITIATION PROTOCOL”, which is hereby incorporated herein by reference.

BACKGROUND

In conventional wireless cellular networks, the initial rollouttypically involves installation of macro base stations to providewireless cellular coverage for mobile units. A macro base stationcomprises multiple transceiver units, outputs relatively high power(that is, 10 watts or more) to its antenna(s) and is communicativelycoupled to a telephone network via a backhaul connection. The backhaulconnection includes a T1 connection (in the United States) or an E1connection (in Europe) to a base station controller (BSC) which is, inturn, connected to a mobile switching center (MSC), and externaltelephone network. Because macro base stations output high power, theycan provide large areas of coverage.

The capacity of a macro base station can be expanded to a limited degreeby the addition of transceivers and antennas to the macro base station.Additional macro base stations can also be added to the cellularnetwork. However, these measures have limitations due to interferenceamong macro base stations as a result of their large coverage areas andhigh output power.

A solution to this capacity problem has been to add micro or pico basestations to the cellular network. Like a macro base station, a microbase station comprises multiple transceiver units and is communicativelycoupled to a telephone network via a backhaul connection to the BSC andMSC. However, compared to the output power of a macro base station, amicro base station outputs relatively lower power (that is, in the rangeof 1-2 watts) to its antenna(s). A conventional pico base station isalso typically communicatively coupled to a telephone network via abackhaul connection, but comprises only a single transceiver unit andtypically uses an Internet protocol (IP) backhaul connection in whichvoice signals are converted to IP packets. A conventional pico basestation also outputs even lower power (that is, less than one watt) toits antenna. Pico base stations can be located indoors, such as inoffices, shopping centers, convention centers, and airports. In additionto having lower output power levels, micro and pico base stations forCode Division Multiple Access (CDMA) and broadband wireless protocolsalso support lower capacity levels than macro base stations due to theirreduced processing power.

A drawback to this approach for adding capacity to the network is thatthe micro or pico base stations are located at sites where theadditional capacity is needed and therefore require additionalinfrastructure for each site. Furthermore, they are not easilyaccessible for maintenance or upgrades. Also, because an additionalbackhaul link is required for each micro or pico base station, thebackhaul links tend to increase installation and maintenance expense.Moreover, the coverage provided by the pico base stations is typicallylimited and often problematic in indoor deployments due to walls andbuilding configuration.

Another issue with covering a large area with pico cells is thatcapacity demand is often dynamic with respect to location and loading.As users move about an area the capacity demands will shift to differentlocations. Network designers must often provision excess capacity, whichcan cause many pico cell resources to go underutilized. Also, forbroader band technologies such as Universal Mobile TelecommunicationsSystem (UMTS), Worldwide Interoperability for Microwave Access (WiMAX)and Long Term Evolution (LTE) technologies, scattering multiple picocells with lower output power and capacity to cover larger areas isinefficient due to the co-channel interference created by neighboringcells. Trunking gain can be achieved by distributing a higher level ofcapacity over the entire coverage area rather than individuallydeploying slices of the capacity at various points in the entirecoverage area.

SUMMARY

One embodiment is directed to a system for providing wireless coverageand capacity for a public land mobile network within a building. Thesystem comprises a pico base station comprising multiple transceiverunits. The pico base station is installed in the building. The systemfurther comprises a plurality of antennas located within the building.The plurality of antennas are located remotely from the pico basestation. The pico base station is communicatively coupled to the publicland mobile network. The pico base station is communicatively coupled tothe plurality of antennas.

Another embodiment is directed to a pico base station. The pico basestation comprises a plurality of radio transceivers to transmit andreceive, within a building, wireless traffic using radio frequencyspectrum assigned to a public land mobile network. The pico base stationfurther comprises an interface to communicatively couple the pluralityof radio transceivers to the public land mobile network.

Another embodiment is directed to an enterprise network providingwireless coverage and capacity for a public land mobile network within abuilding located on a premises of an enterprise. The system includes apico base station comprising multiple transceiver units. The pico basestation is installed in the building and is configured to communicateusing licensed radio frequency spectrum. The system further includes aplurality of antennas located within the building. The plurality ofantennas are located remotely from the pico base station. The systemfurther includes a distributed antenna unit to communicatively coupledthe pico base station to the plurality of antennas. The pico basestation is communicatively coupled to the public land mobile network.

The details of various embodiments of the claimed invention are setforth in the accompanying drawings and the description below. Otherfeatures and advantages will become apparent from the description, thedrawings, and the claims.

DRAWINGS

FIG. 1 illustrates one embodiment of a system for providing improvedwireless capacity and coverage in a building.

FIG. 2 is a block diagram of an embodiment of a multiple-TRX pico basestation.

FIG. 3 is a block diagram of an embodiment of a multiple-TRX pico basestation.

FIG. 4 is a block diagram of an embodiment of a multiple-TRX pico basestation.

FIG. 5 illustrates one example of a distributed architecture for anenterprise mobile network.

FIG. 6 illustrates an example of an architecture for an enterprisemobile network.

FIG. 7 illustrates an example of an architecture for an enterprisemobile network.

FIG. 8 illustrates an example of an architecture for an enterprisemobile network.

FIG. 9 illustrates an example of an architecture for an enterprisemobile network.

FIG. 10 illustrates an example of an architecture for an enterprisemobile network.

FIG. 11 illustrates a usage scenario in which the technology describedhere is used to provide wireless local loop (WLL) service for both voiceand data within an enterprise.

FIG. 12 illustrates a usage scenario in which the technology describedhere is used to provide only roaming service within an enterprise.

FIG. 13 illustrates a usage scenario in which an enterprise mobilenetwork is configured to support both local subscribers and “hybrid”subscribers.

FIG. 14 illustrates a usage scenario in which an enterprise mobilenetwork includes a Private A-link Intelligent Multiplexer (PALIM)switching function.

FIG. 15 illustrates an example in which an enterprise mobile network isimplemented across two offices of an enterprise.

FIG. 16 illustrates an example in which two separate enterprise mobilenetworks share a GSN and MSS.

FIG. 17 illustrates an example in which an IP PBX is integrated with anenterprise mobile network.

FIG. 18 illustrates an example in which an access gateway is integratedwith an enterprise mobile network.

FIG. 19 illustrates an example of an enterprise mobile network.

FIG. 20 illustrates an example of an enterprise mobile network.

FIG. 21 illustrates an example of an enterprise mobile network.

FIG. 22 illustrates an example of an enterprise mobile network.

FIG. 23 illustrates how a mobile device is registered with the IP PBX ofFIG. 22 in connection with a location update.

FIG. 24 illustrates how a mobile device that is camped onto theenterprise mobile network of FIG. 22 can make a call to a deviceconnected to the PSTN.

FIG. 25 illustrates how a call that is made to a MSISDN numberassociated with a local subscriber can be completed in the enterprisemobile network shown in FIG. 22 .

FIG. 26 illustrates how a call that is made to a PBX extension numberassociated with a local subscriber can be completed in the enterprisemobile network shown in FIG. 22 .

FIG. 27 illustrates an example of an enterprise mobile network.

FIG. 28 illustrates an example of how a telephone call made to PBXextension associated with a local subscriber of an enterprise is handledin the enterprise mobile network shown in FIG. 27 .

FIG. 29 illustrates an example in which someone uses a fixed SIP phoneto call a user's PBX extension.

FIG. 30 illustrates an example in which someone uses a mobile device tocall a user's local MSISDN number.

FIG. 31 illustrates an example in which someone uses a UC end point tocall a user's UC end point.

FIG. 32 illustrates an example in which a computer/telephone integration(CTI) application installed on a UC end point is used to remotelycontrol a mobile device.

FIG. 33 illustrates an example deployment of an enterprise mobilenetwork that includes a virtual IP PBX.

FIG. 34 is illustrates the use of security gateway (SEG) functionalityin an enterprise mobile network.

FIG. 35 illustrates how SIP-server functionality can be integrated intoan MSS as a part of a FMC solution.

FIG. 36 illustrates how a SIP User Agent can be implemented in a basestation subsystem.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 illustrates one embodiment of a system 100 for providing improvedwireless capacity and coverage in a building 134. In the particularembodiment shown in FIG. 1 , the system 100 comprises a multiple-TRXpico base station 102 that is communicatively coupled to a public landmobile network (PLMN) 104 via a backhaul link 106. Within the network104, the backhaul link 106 is coupled to a base station controller (BSC)108, which is, in turn, coupled to a network switching subsystem (NSS)110. The NSS 110 is coupled to a public switched telephone network(PSTN) 112 (e.g., for voice communications) and to other public landmobile networks 105. Also, the BSC 108 is communicatively coupled to oneor more data nodes (for example, a Serving GPRS Support Node (SGSN)) forcommunicatively coupling the BSC 108 (and the multiple-TRX pico basestation 102) to one or more data networks 114 such as the Internet(e.g., for data communications). Although the terms BTS, BSC, and BSSare used throughout the following description, it is to be understoodthat the concepts described here can also be applied to embodiments thatmake use of network elements that are referred to using other terms,such as Node B, eNB, RNC, and radio access network (RAN) that are morefrequently associated with 3G and 4G networks.

The BSC 108 performs various conventional BSC functions including radiochannel allocation, call handovers among base stations, configuring themultiple-TRX pico base station 102, handling alarms and performingnetwork management functions. The BSC 108 includes or is communicativelycoupled to an appropriate network element (for example, a packet controlunit (PCU)) for directing traffic to and from the data network 114.

The NSS 110 performs various conventional functions including circuitswitching, and providing applications and call features to mobilesubscribers, such as call ringing and roaming. For example, the NSS 110typically includes a mobile switching center (MSC) and otherfunctionality such as a home location register (HLR) and visitorlocation register (VLR). In one embodiment, certain of the featuresconventionally performed by the BSC 108 and NSS 110 may instead beperformed by the multiple-TRX pico base station 102. For example, themultiple-TRX pico base station 102 may include a local server which isconfigured with a Linux (or other) operating system to implement thesefunctions.

The multiple-TRX pico base station 102 comprises multiple transceiverunits (TRXs) 116. In one implementation, the multiple-TRX pico basestation 102 comprises two TRXs 116. However, it is to be understood thata greater number of TRXs can be included in the multiple-TRX pico basestation 102 (for example, 4 TRXs). Each of the TRXs 116 is used tooutput a low power (specifically, less than one watt) RF channel. In oneimplementation, the multiple TRXs 116 are implemented as a multi-carrierradio card comprising one or more digital signal processors (DSP) thatproduce and process baseband downlink and uplink wireless signals foreach of the multiple RF channels supported by the multiple TRXs 116, oneor more upconverters to upconvert downlink wireless baseband signals toappropriate RF frequencies, and one or more downconverters todownconvert uplink RF signals received by the radio card to wirelessbaseband signals for processing by the one or more DSPs. Such amulti-carrier radio card also includes other conventional base stationcomponents known to those skilled in the art including, for example,filters and amplifiers (for example, an appropriate amplifier to causethe radio card to output low power RF signals). It is to be understoodthat the various components described here (for example, amplifiers) canbe implemented separately from such a multiple-carrier radio card orTRXs 116. Moreover, each of the multiple TRXs 116 can also beimplemented in other ways. For example, a separate radio card can beused to implement each of the multiple TRXs 116.

The multiple-TRX pico base station 102 comprises a suitable interface115 to communicatively couple the multiple-TRX pico base station 102(and the TRXs 116 included therein) to the network 104. In oneembodiment, the multiple-TRX pico base station 102 uses an Internetprotocol (IP) backhaul connection in which voice and data signals areconverted to IP packets for the communication via the backhaul link 106to the BSC 108 (for example, using a cable modem or DSL modem).Alternatively, the multiple-TRX pico base station 102 may use a T1 or E1connection (that is, a time division multiplexing (TDM) connection) forthe backhaul link 106. Alternatively, a wireless link (for example, aWIMAX wireless link) can be used to provide the backhaul link 106, inwhich case the interface 115 would comprise a suitable WIMAX interface.It is noted in this regard that only a single backhaul link 106 need beprovided in order to service the multiple TRXs 116 that are included inthe multiple-TRX base station 102. This is in contrast to conventionalpico base station deployments in which multiple, single TRX pico basestations are deployed, each of which requires a separate backhaul link.

In a GSM implementation of the embodiment shown in FIG. 1 , the GSMA-bis interface is used to communicate between the multiple-TRX picobase station 102 and the BSC 108 over the backhaul connection 106. Insuch a GSM implementation, the BSC 108 communicates with an MSC in theNSS 110 using the GSM A interface and a packet control unit of the BSC108 communicates with a SGSN in the data network 114 using the GPRS Gbinterface. In one such implementation, the various interfaces areimplemented in software executing on the multiple-TRX pico base station102. A BSC 108 can communicate with one or more multiple-TRX pico basestations 102.

Each of the transceiver units 116 communicates in a singlebi-directional RF channel of a particular licensed wireless RFcommunications band. Each such bi-directional RF channel comprises anupstream channel and downlink channel. In one exemplary implementation,each of the transceiver units 116 of the multiple-TRX pico base station102 transmits and receives 200 kHz GSM uplink and downlink RF channelswithin the 850 MHz frequency band (for example, 824-849 MHz uplink and869-894 MHz downlink). In another exemplary embodiment, each of thetransceiver units 116 of the multiple-TRX pico base station 102transmits and receives in 1.25 MHz CDMA uplink and downlink RF channelswithin the 1900 MHz frequency band (for example, 1850-1910 MHz uplinkand 1930-1990 MHz downlink). In other embodiments, the transceiver units116 support other wireless protocols (for example, other GSM bands,other CDMA bands and GPRS, EDGE, UMTS, W-CDMA, LTE, EVDO, CDMA2000, UMB,HSPA, and WIMAX protocols). Moreover, it is to be understood that themultiple-TRX pico base station 102 may support multiple, differentwireless protocols so that the different wireless protocols can besupported by a single multi-mode multiple-TRX pico base station 102. Forexample, one transceiver 116 may support one wireless protocol whileother transceivers 116 may support other wireless protocols.

In the particular embodiment shown in FIG. 1 , the multiple-TRX picobase station 102 is also communicatively coupled to a distributedantenna system (DAS) 118. The DAS 118 comprises a multi-port repeaterhub 120 which is communicatively coupled to a plurality of antenna units122. Each antenna unit 122 includes or is coupled to at least oneantenna 124 from which the antenna unit 122 receives and radiates RFsignals.

The DAS 118 is used to provide RF wireless coverage from the remotelylocated and spatially separated antenna units 122 using the capacitythat is provided by the multiple-TRX pico base station 102. This incontrast to conventional pico base station deployments in whichmultiple, single-TRX pico base stations are located throughout thecoverage area (that is, each such single-TRX pico base station isco-located with the antenna from which that base station transmits andreceives the single RF channel). With the embodiment shown in FIG. 1 ,the TRXs 116 of the pico base stations 102 are centralized and can belocated in a secure location (for example, a utility or server closet orroom).

In the particular embodiment shown in FIG. 1 , the hub 120 iscommunicatively coupled to the antenna units 122 via one or moreintermediate expansion hubs 126. In such an embodiment, the hub 120 iscommunicatively coupled to each of the expansion hubs 126 via one ormore cables 128. For example, in one embodiment described here inconnection with FIG. 1 , the cables 128 comprise one or more fiber opticcables. The antenna units 122 are communicatively coupled to theexpansion hub 126 via appropriate cabling 130 (for example, thin coaxialcabling, CATV cabling, or fiber optic cabling). In other embodiments,the antenna units 122 may be communicatively coupled to the hub 120directly without the use of intermediate expansion hubs 126.

In one implementation of such an embodiment, the hub 120 receives adownlink RF channel from each of the transceiver units 116 included inthe multiple-TRX pico base station 102. The hub 120 downconverts eachsuch downlink RF channel to an intermediate frequency (IF) fordistribution to the antenna units 122. The downconverted IF channels arecombined and communicated to each expansion hub 126 over a respectivefiber link 128 using an analog optical modulator. Each expansion hub 126receives and demodulates the optical signal to recover the combineddownlink IF signal, which is then transmitted to each of the antennaunits 122 that are coupled to that expansion hub 126 using the cabling130. Each antenna unit 122 receives the combined IF signal and separatesthe IF signals into separate IF signals for each downlink RF channelreceived from the multiple-TRX pico base station 102. The antenna unit122 then upconverts each such separated IF signal to its original RFfrequency as was received from pico base station 102. The upconverteddownlink RF signals are then combined and radiated from an antenna 124coupled to the antenna unit 122.

A similar process is performed in the uplink direction. At each antennaunit 122, RF signals that are received from the antenna 124 coupled tothat antenna unit 122 are filtered in order to produce an uplink RFchannel for each of the transceiver units 116 included in themultiple-TRX pico base station 102. The antenna unit 122 downconvertseach such uplink RF channel to an intermediate frequency (IF) fordistribution back to the hub 120 via an expansion hub 126. Thedownconverted IF channels are combined and communicated to eachexpansion hub 126 over a cable 130. Each expansion hub 126 combines thevarious IF channels it receives from the antenna units 122 that arecoupled thereto and communicates the combined IF channels to the hub 120over a fiber link 128 using an analog optical modulator. The hub 120receives and demodulates the optical signal from each expansion hub 126to recover the combined IF signal transmitted from that expansion hub126. The recovered combined IF signals from all of the expansion hubs126 are then combined. The hub 120 then separates the combined IFsignals into separate IF signals for each uplink RF channel supported bya transceiver unit 116 in the multiple-TRX pico base station 102. Thehub 120 then upconverts each such separated IF signal to its original RFfrequency as was received over the air. Each upconverted uplink RFchannel is then communicated to a respective transceiver unit 116 in themultiple-TRX pico base station 102.

In other embodiments, separation of the signals is not required if theIF and RF frequencies are selected such that a block upconverters andblock downconverters can be used (instead of using separate, individualnarrowband upconverters and downconverters). In the simplest example ofsuch an embodiment, if the system were designed to distributemulti-carrier GSM in the 900 MHz band and each carrier were located atthe correct frequency offset from each other, the entire IF spectrumcould be upconverted as one continuous block versus having individualnarrow band upconverters and likewise with the downconversion of the RFspectrum

The DAS 118 may include one or more of the following filtering,amplification, wave division multiplexing, duplexing, synchronization,and monitoring functionality as needed and as is known in the art. Also,power may also be provided to the antenna units 122 over the cabling 130such that no additional power source is needed to power the antennaunits 122. One example of a suitable DAS 118 is the InterReach FUSIONin-building distributed antenna system that is commercially availablefrom ADC Telecommunications, Inc., of Eden Prairie, Minn.

Although one particular type of DAS is shown in FIG. 1 , it is to beunderstood that other DAS networks and configurations can used in otherembodiments. Such alternative DAS networks and configurations include,without limitation, the use of multiple, overlaid single band analog IFDAS networks (for example, using unshielded twisted pair or CAT5cabling), DAS networks that do not employ any expansion hubs, DASnetworks that make use of digital radio frequency transport, and“passive” DAS networks. Moreover, the wireless signals communicatedbetween the multiple-TRX pico base station 102 and the antennas 124 canbe transported in one or more of the following forms: analog RF form,analog IF form, analog baseband form, digitized RF form, digitized IFform, and digitized baseband form.

The multiple-TRX pico base station 102 and the hub 120 of the DAS 118are installed in a building 134 in which coverage and capacity is to beprovided. The building 134 is not controlled by the service providerthat operates the network 104. That is, the building 134 comprises acustomer premise that is owned, controlled, or otherwise used by aperson or entity other than the service provider that operates thenetwork 104, such as an “enterprise” (for example, an “enterprise” suchas a business, non-profit organization, or government entity). Examplesof such buildings include, without limitation, office buildings,shopping centers, educational or governmental buildings, airports,sports or entertainment arenas or stadiums, hospitals, single familyhomes, condominiums, apartments, or hotels or motels.

In one implementation of such an embodiment, the multiple-TRX pico basestation unit 102 and hub 120 of the DAS 118 are installed within a rack136 that is included in a utility or server room or closet of thebuilding 134. In the particular embodiment shown in FIG. 1 , at least aportion of such equipment is “rack mountable”. That is, at least aportion of such equipment is packaged in such a way to fit within one ormore standard racks 136 located within the utility room. Such racks 136enable such rack-mountable equipment to be stacked within the rack in anefficient, organized, and standard manner. One example of such a rack isa 19-inch rack (for example, a 19-inch rack that complies with one ormore of the following standards: Electronic Industries Alliance (EIA)310-D, International Electrotechnical Commission (IEC) 60297 andDeutsches Institut für Normung e.V (DIN) 41494 SC48D).

In the embodiment shown in FIG. 1 , the multiple-TRX pico base station102 and the hub 120 are rack mountable. That is, each respective chassisin which the various components of the multiple-TRX pico base station102 and the hub 120 are housed and designed to fit (and be installed) inthe rack 136. Each such chassis includes appropriate fastening andstructural support elements to fasten the multiple-TRX pico base station102 and the hub 120 to the rack 136 and to support the multiple-TRX picobase station 102 and the hub 120 when installed in the rack 136.

In another embodiment, the base station 102 and the hub 120 are housedwithin the same physical chassis (for example, the same rack-mountablephysical chassis).

Together, the antenna units 122 form one or more coverage areas. Theantenna units 122 are distributed throughout the building 134 so as toform one or more coverage areas that substantially include the occupiedareas within the building 134.

Mobile communications equipment 132 (e.g., a cell phone) within acoverage area is communicatively coupled to the network 104 via one ormore of the antenna units 122, an expansion hub 126, the hub 120, themultiple-TRX pico base station 102 and the backhaul 106.

Centralizing the multiple-TRX pico base station 102 and thendistributing the aggregated capacity provided by the multiple-TRX picobase station 102 is more efficient in terms of resource utilization,including frequency spectrum, than conventional pico base stationdeployment approaches, which may result in underutilization of pico cellresources.

The multiple-TRX pico base station 102 shown in FIG. 1 is describedabove as sending and receiving RF signals with the DAS 118. It is to beunderstood that in other embodiments, the transceivers 116 of themultiple-TRX pico base station 102 sends and receives other types of thesignals (which are distributed by the DAS 118 and which are ultimatelyused to produce an RF signal in the downlink and which were originallyreceived as an RF signal in the uplink). For example, the transceivers116 and the DAS 118 can communicate using IF signals, in which case, inthe downlink, the transceivers 116 upconvert the downlink basebandsignals to appropriate IF frequencies and, in the uplink, the DAS 118provides IF signals to the transceivers 116, which downconvert thereceived IF signals to baseband for processing. Similarly, analogbaseband signals or digital data can be communicated between thetransceivers 116 and the DAS 118 (in which case, in the downlinkdirection, the RF signals are ultimately produced in the DAS 118 and, inthe uplink direction, the DAS 118 receives the original RF signals frommobile equipment 132 and processes the RF signals in order to producethe desired signal for communication to the transceivers 116).

FIG. 2 is a block diagram of an alternative embodiment of a multiple-TRXpico base station 202. As with the multiple-TRX pico base station 102shown in FIG. 1 , the multiple-TRX pico base station 202 shown in FIG. 2comprises multiple TRXs 116. The multiple-TRX pico base station 202 ofFIG. 2 , however, also comprises at least a portion of the base stationcontroller functionality 208 necessary to control the multiple TRXs 116included in the multiple-TRX pico base station 202 and for themultiple-TRX pico base station 202 to communicate with a PLMN 204 (forexample, with the NSS 110 and/or a data network 114). In oneimplementation of such an embodiment, the base station controllerfunctionality 208 is implemented in software that executes on one ormore programmable processors that are included in the multiple-TRX picobase station 202.

In a GSM implementation of such an embodiment, the BSC functionality 208implements at least a portion of the GSM A interface in order tocommunicate with the NSS 110 over the backhaul 106 and implements atleast part of the GPRS Gb interface in order to communicate with a SGSNincluded in the data network 114.

Otherwise, the items shown in FIG. 2 that are referenced in FIG. 2 usingthe same reference numerals as used in FIG. 1 are substantially the sameas described above in connection with FIG. 1 .

In other embodiments, the BSC functionality 208 further comprises atleast some MSC-related functionality. FIG. 3 is a block diagram of onesuch alternative embodiment of a multiple-TRX pico base station 302. Aswith the multiple-TRX pico base stations 102 and 202 shown in FIGS. 1and 2 , the multiple-TRX pico base station 302 shown in FIG. 3 comprisesmultiple TRXs 116. As with the multiple-TRX pico base station 202 shownin FIG. 2 , the multiple-TRX pico base station 302 of FIG. 3 alsoincludes base station control functionality 308 necessary to control themultiple TRXs 116 included in the multiple-TRX pico base station 302 andfor the multiple-TRX pico base station 302 to communicate with a PLMN304 (for example, with the public NSS 110 and/or a data network 114). Inone implementation of such an embodiment, the base station controllerfunctionality 308 is implemented in software that executes on one ormore programmable processors that are included in the multiple-TRX picobase station 302.

The multiple-TRX pico base station 302 shown in FIG. 3 also includes NSSfunctionality 310. For example, in the particular embodiment shown inFIG. 3 , the NSS functionality 310 implements at least a portion of thecall switching functionality normally implemented in a MSC (for example,GSM media gateway (MGW) functionality 340). In particular, when onemobile device that is communicating with the multiple-TRX pico basestation 302 (for example, mobile equipment A in FIG. 3 ) calls anothermobile device that is communicating with the multiple-TRX pico basestation 302 (for example, mobile equipment B in FIG. 3 ), the MGWfunctionality 340 in the multiple-TRX pico base station 302 is able tolocally switch the call traffic for that call when instructed to do soby a public MSC included in the public NSS 110. In this way, the calltraffic need not be backhauled back to the public MSC in the public NSS110 and only the signaling traffic necessary to establish the callsneeds to be backhauled to the public MSC. In such an embodiment, the NSSfunctionality 310 implements an appropriate interface (for example, theGSM Mc interface) between the MGW functionality 340 and the public MSCin order to permit the public MSC to control the MGW functionality 340via the backhaul link 106.

In one implementation of such an embodiment, the NSS functionality 310is implemented in software that executes on one or more programmableprocessors that are included in the multiple-TRX pico base station 310(for example, the same one or more processors that execute the softwarethat implements the BSC functionality 308).

Otherwise, the items shown in FIG. 3 that are referenced in FIG. 3 usingthe same reference numerals as used in FIG. 1 are substantially the sameas described above in connection with FIG. 1 .

In other implementations, other NSS-related functionality is implementedwithin the multiple-TRX pico base station 302 including, withoutlimitation, at least some MSC server functions. FIG. 4 is a blockdiagram of one such alternative embodiment of a multiple-TRX pico basestation 402. As with the multiple-TRX pico base stations 102, 202, and302 shown in FIGS. 1-3 , the multiple-TRX pico base station 402 shown inFIG. 4 comprises multiple TRXs 116. As with the multiple-TRX pico basestation 302 shown in FIG. 3 , the multiple-TRX pico base station 402 ofFIG. 4 also includes base station control functionality 408 necessary tocontrol the multiple TRXs 116 included in the multiple-TRX pico basestation 402 and for the multiple-TRX pico base station 402 tocommunicate with a PLMN 404 (for example, with the public NSS 110 and/ora data network 114). In one implementation of such an embodiment, thebase station controller functionality 408 is implemented in softwarethat executes on one or more programmable processors that are includedin the multiple-TRX pico base station 402.

In the embodiment shown in FIG. 4 , the multiple-TRX pico base station402 comprises NSS functionality 410. The NSS functionality 410 includesMGW functionality 440 as described above in connection with FIG. 3 . TheNSS functionality 410 in the embodiment shown in FIG. 4 also implementsprivate GSM MSC server functionality (MSC-S) 442 and a private homelocation register (HLR) 444. The private MSC-S functionality 442 and theprivate HLR 444 enable the NSS functionality 410 to perform fullmobility management and call management for calls between mobilestations 132 that are communicating with the multiple-TRX pico basestation 402 or between one or more mobile stations 132 that arecommunicating with the multiple-TRX pico base station 402 and one ormore pieces of fixed equipment 456 (or other SIP entities) that arelocated within the building 134. In the particular embodiment shown inFIG. 4 , the fixed equipment 456 comprises voice over IP (VOIP)telephones that are communicatively coupled to an IP PBX 454 over acorporate IP local area network (LAN) 450. In such an embodiment, theNSS functionality 410 further comprises a Session Initiation Protocol(SIP) agent 452 to enable the private MSC-S functionality 442 and the IPPBX 454 to use the SIP protocol to establish sessions between the mobileequipment 132 (which do not otherwise support the SIP protocol) and thefixed equipment 456. Also, the SIP agent 452 enables the private MSC-Sfunctionality 442 to establish sessions with other network entities thatsupport the SIP protocol including, for example, a unified communicationserver 458 (for example, the MICROSOFT OFFICE COMMUNICATIONS SERVER2007). As a result, such sessions can be established without using thePSTN 112 or the PLMN 404. However, the private MSC-S functionality 442can be configured to support call handovers to the PLMN 404 or otherPLMN 105 in the event that such a mobile station 132 moves outside ofthe coverage area of the pico base station 402 while such a session isstill in progress. Likewise, the private MSC-S functionality 442 can beconfigured to support inbound handovers from another MSC when such amobile station 132 comes into the coverage area of the pico base station402.

In such an embodiment, the MGW functionality 440 communicates, forexample, with a SIP session border controller (SBC) 460 in order tocommunicate the call traffic between the mobile equipment 132 and thefixed equipment 456 (or other SIP entities) and perform any transcodingthat is required.

In the embodiment shown in FIG. 4 , the private MSC-S functionality 442and private HLR 444 are “private” in the sense that such functionalityis only used for establishing sessions among licensed-RF-spectrum mobilestations 132 that are in the private HLR 444 and SIP-enabled equipmentthat is communicatively coupled to the corporate IP LAN 450. In such anembodiment, each mobile station 132 that is in the private HLR 44 isalso in a public HLR within the PLMN 404. In the event that a mobilestation 132 that is in the private HLR 444 makes a call to a mobilestation that is not in the private HLR 444 or to a fixed device that isnot coupled to the corporate IP LAN 450, the MSC-S functionality of thepublic MSC is used to establish such a call, in which case the publicMSC interacts with pico base station 402 in the conventional manner.Likewise, if a mobile that is not in the private HLR 444 uses the picobase station 402 to establish a call, the MSC-S functionality of thepublic MSC in the public NSS 110 is used to establish such a call(directly or by interacting with another public NSS), in which case thepublic MSC in the NSS 110 interacts with pico base station 402 in theconventional manner. In other embodiments, the MSC-S functionality andHLR integrated into the pico base station 402 is “public” and acts asconventional MSC-S and HLR in such scenarios (for example, by includingother NSS functionality such as a visitor location register (VLR) andprepaid services (PPS)).

In the embodiment shown in FIG. 4 , features that are provided by theunified communication server 458 (for example, a voice message-to-emailgateway or conference calling) to SIP-enabled devices can be provided tothe non-SIP-enabled mobile devices that are in the private HLR 444.

Moreover, the private MSC-S functionality 442 can be configured to routecalls from mobile equipment 132 to the PSTN 112 via the IP PBX 454 andits connection to the PSTN 112 (for example, where doing so results inthe least cost to the enterprise).

Likewise, supplemental services can be implemented locally using the IPPBX 454 and the private MSC-S functionality 442 of the multiple-TRX picobase station 402. For example, a user who has both a fixed VOIPtelephone coupled to the IP PBX 454 and a mobile device thatcommunicates with the multiple-TRX pico base station 402 can haveoutside calls that come into either device forwarded to the other devicesuch that both devices ring when such an outside calls comes in.Moreover, voice mail messages that are received via either device can berouted to the unified communication server 458 (for example, fordelivery via a user's email account), thereby providing a singlerepository of voice mail messages.

The above-mentioned enhanced SIP-related features can be provided tolicensed-RF-spectrum (i.e., GSM) mobile devices that are in the privateHLR 444 while still permitting other licensed-RF-spectrum mobile devicesto communicate with the PLMN 404 or another PLMN 105 using conventionalcellular technology.

In one implementation of such an embodiment, the NSS functionality 410is implemented in software that executes on one or more programmableprocessors that are included in the multiple-TRX pico base station 410(for example, the same one or more processors that execute the softwarethat implements the BSC functionality 408).

Otherwise, the items shown in FIG. 4 that are referenced in FIG. 4 usingthe same reference numerals as used in FIG. 1 are substantially the sameas described above in connection with FIG. 1 .

The functionality described above in connection with FIGS. 3 and 4 can,in other embodiments, also be implemented using base stations other thanmultiple-TRX pico base stations (for example, using single-TRX pico basestations, micro base stations, and macro base stations). Moreover, suchfunctionality is described above as being implemented in an integratedbase station device. It is to be understood, however, that in some otherembodiments, such functionality is implemented using separate networknodes.

The various elements described above (for example, the multiple-TRX picobase station and the DAS coupled thereto) can be deployed in variousarchitectures and usage scenarios.

FIG. 5 illustrates one example of a distributed architecture 500 inwhich the technology described above (for example, a multiple-TRX picobase station and DAS) can be deployed to provide coverage and capacityto GSM/GPRS mobile devices while in an enterprise 502. In this example,a pico base station subsystem 504 is coupled to a DAS 506. The pico basestation 504 is communicatively coupled to a corporate IP local areanetwork 508 (using a GSM Ater-over-IP interface for calls and a GPRSGb-over-IP interface for data). The corporate IP LAN 508 is used to gainaccess to the wireless service operator's central office 510 via an IPNetwork 512, where a MSC server (MSC-S) 514, a media gateway (MGW) 516,and GSN 518 are located. In the embodiment shown in FIG. 5 , a router532 is used to communicatively couple the IP network 512 to the variouselements of the operator's central office 510.

The MSC-514 handles signaling traffic routed to the central office 510and controls the MGW 516. In the particular embodiment, the MSC-S 514includes a SIP user agent (UA) 530 to handle SIP-related signaling (asdescribed below). The MGW 516 switches calls and performs any neededmedia conversion (for example, conversions between formats used in theenterprise 502 and formats used in the public switched telephone networkor by a another PLMN (collectively shown at reference numeral 526 inFIG. 5 )). The GSN 518 is also coupled to an IP network 528 (over the Gbinterface) and implements conventional SGSN functionality.

In such an embodiment, the NSS functionality is centralized in thecentral office 510 while the base station subsystem (BSS) is located inthe enterprise 502. In such an example, the pico base station subsystem504 implements functionality similar to that described above inconnection with FIGS. 3 and 4 to enable the pico base station subsystem504 to locally switch sessions among mobiles 520 that are within itscoverage area and/or sessions with an IP PBX 522 (and the SIP phones 534coupled thereto). In this example, the IP PBX 522 and the SIP phones 534are coupled to the pico base station subsystem 504 over the corporatelocal area network 508 using a SIP session border controller (SBC) 524,which manages the signaling and media streams for sessions establishedwith such devices (implementing, for example, a Back-to-BackUser-Agent). The SBC 524 handles, for example, transcoding and NATtraversal (using, for example, the Interactive ConnectivityEstablishment (ICE) protocol or the Session Traversal Utilities for NAT(STUN) protocol).

In this embodiment, the NSS functionality is centralized and located inthe operator's central office 510, which makes it easier to maintainsuch NSS functionality. However, firewalls are typically used tocommunicatively couple such NSS functionality to the pico base stationsubsystem 504 in the enterprise 502, some mechanism (for InternetProtocol Security (IPsec) software) is typically used to securecommunications among these devices, and some mechanism is used toprioritize data flows and to help ensure a desired quality of service(QOS) for communications among these devices using the Internet.Moreover, communications between the NSS functionality located in theoperator's central office 510 and the pico BSS 504 in the enterprise 502involve at least one Network Address Translation (NAT) traversal.

FIG. 6 illustrates another architecture 600 for an enterprise mobilephone system 601 where an enterprise 602 connects a media gateway (MG)604 and a mobile switching center server (MSS) 606 to the enterprise'sIP-based Intranet 608. In each office 603 of the enterprise 602, a picobase station subsystem 610 and a DAS 612 are installed and are coupledto the MG 604 and MSS 606 via the enterprise's Intranet 608. In thisway, the pico BSS/DAS equipment installed in the various offices 603 ofthe enterprise 602 can share the MG 604 and MSS 606 via the Intranet608. The MG 604 and the MSC-S 606 are communicatively coupled to awireless operator's PLMN 616 using a suitable backhaul link (forexample, TDM links). In this example, the pico BSS 610, DAS 612, MG 604,MSS 606, and the Intranet 608 are located in the enterprise.

The elements of the enterprise mobile phone system 601 arecommunicatively coupled to one another using the Intranet 608 (the solidlines between such elements and the Intranet 608 depict IP communicationlinks). SS7 and GSM compatible signaling (for example, signalingformatted according to the ISDN user part (ISUP) and mobile applicationpart (MAP) protocols) are communicated between nodes in the operator'sPLMN 616 and the MSS 606 and between the MSS 606 and the pico BSS 610.SS7-related signaling is shown in FIGS. 6-10 using dashed lines. Thecall-related media streams are communicated between the pico BSS 610 andthe MG 604 using the Real-time Transport Protocol (RTP). The MSS 606controls the various media gateway functions in the system 601 using,for example, the Media Gateway Control Protocol (MGCP). In thisembodiment, SIGTRAN is also used to communicate signaling data over theIP links.

In this example, external devices (not shown) are communicativelycoupled to the enterprise mobile phone system 601 via the operator'sPLMN 616. Calls between external communication devices (not shown) andmobile devices 618 serviced by the pico BSS 610 are setup using the MSS606 and the associated media streams are switched by the MG 604.

FIG. 7 illustrates an architecture 700 that is similar to the one shownin FIG. 6 (and those elements that are the same as the ones used in theexample shown in FIG. 6 are referenced in FIG. 7 using the samereference numerals used in FIG. 6 ). Architecture 700 is extended tofurther include an enterprise IP phone system 720 that is deployed inthe enterprise. The enterprise IP phone system 720 includes an IP PBX722 that supports communications with SIP phones 724. In thisembodiment, a SIP Session Border Controller (SBC) 726 is used to couplethe SIP phones 724 to Intranet 608. The SBC 726 manages the signalingand media streams for sessions established with such devices andperforms any needed transcoding.

The MSS 606 includes a SIP user agent (SIP UA) 614 to set up sessionsbetween mobiles 618 that are being handled by the pico BSS 610 and SIPPhones 724 or the IP PBX 722. Sessions between such mobiles 618 anddevices that are coupled to the PSTN 728 can be setup using the SIP UA614 and the connection to the PSTN 728 provided by the IP PBX 722.Alternatively, sessions between such mobiles 618 and devices that arecoupled to the PSTN 728 can be routed through the operator's PLMN 616(as is the case with the example shown in FIG. 6 ).

Note that in both of the architectures shown in FIGS. 6 and 7 , afirewall is not used to couple the MSS 606, MG 604, and each of the picoBSSs 610 to the Intranet 608. Also, IPSec and SRTP are not needed tosecure communications among these devices. If the intranet backhaulbandwidth and QOS is sufficient to support the services provided by theenterprise mobile phone system 601 (for example, by using a dedicatedVPN) then special QOS features and devices are not required to providesuch backhaul. If backhaul QOS is an issue, a resource reservationmechanism may be needed to prioritize data flows and to help ensure adesired quality of service. Moreover, in the examples shown in FIGS. 6and 7 , the MSS 606, MG 604, and each of the pico BSSs 610 are assigneda respective Intranet IP address, and communications among those devicesdo not involve any NAT traversals.

FIG. 8 illustrates an architecture 800 that is similar to the one shownin FIG. 6 (and those elements that are the same as the ones used in theexample shown in FIG. 6 are referenced in FIG. 8 using the samereference numerals used in FIG. 6 ).

The example architecture 800 shown in FIG. 8 is similar to the exampleshown in FIG. 6 except that the MSS 606, MG 604, and pico BSSs 610 arecoupled to one another over the public Internet 830 instead of anenterprise's Intranet. As a result, firewalls 832 are needed to couplethe MSS 606, MG 604, and each pico base station subsystem 610 to theInternet 830. Also, IPSec and SRTP are used to secure communicationsamong these devices, and QOS is used to prioritize data flows and tohelp ensure a desired quality of service for communications among thesedevices using the Internet 830. Moreover, each of the MSS 606, MG 604,and each pico base station subsystem 610 is assigned an Internet IPaddress, and communications among those devices occurs over the Internet830.

FIG. 9 illustrates an example architecture 900 that is similar to theone shown in FIGS. 7-8 (and those elements that are the same as the onesused in the examples shown in FIGS. 7-8 are referenced in FIG. 9 usingthe same reference numerals used in FIGS. 7-8 ).

The example architecture 900 shown in FIG. 9 is similar to the exampleshown in FIG. 7 except that the one shown in FIG. 9 uses an enterprise'sIntranet 934 and the Internet 830 to integrate an IP PBX 722 and SIPPhones 724 into the system. In this example, the SIP user agent (SIP UA)614 included in the MSS 606 is used to set up sessions between mobiles618 that are being handled by the MSC-S 606 and SIP Phones 724 or the IPPBX 722. Sessions between mobiles 618 and the PSTN 728 can be setupusing the SIP UA 614, in which case the connection to the PSTN 728 isprovided by the IP PBX 722. In this example, the SBC 726, IP PBX 722 andSIP Phones 724 are located behind the firewall 832 that stands betweenthe Intranet 934 and the Internet 830. Thus, the IP PBX 722 and SIPPhones 724 are assigned Intranet IP addresses, and communications thatgo through the SBC 726 involve a NAT traversal. In this embodiment, theSBC 726 manages the signaling and media streams for sessions establishedwith such devices (implementing, for example, a Back-to-BackUser-Agent). Also, the SBC 726 handles, for example, transcoding and NATtraversal (using, for example, the Interactive ConnectivityEstablishment (ICE) protocol or the Session Traversal Utilities for NAT(STUN) protocol).

In this example, IPSec and SRTP are needed to secure communicationsamong the MSS 606, MG 604, the pico BSSs 610, and the enterprise IPphone system 720 that occur over the Internet 830. Also, QOS is neededto prioritize data flows and to help ensure a desired quality of servicefor communications among the MSS 606, MG 604, and the pico BSSs 610 thatoccur over the Internet 830.

FIG. 10 illustrates an example architecture 1000 that is similar to theexample shown in FIG. 9 (and those elements that are the same as theones used in the example shown in FIG. 9 are referenced in FIG. 10 usingthe same reference numerals used in FIG. 9 ).

The example architecture 1000 shown in FIG. 10 is similar to the exampleshown in FIG. 9 except that each pico BSS/DAS deployment is also coupledto an enterprise's Intranet 934. As a result, each pico base station 610is assigned an Intranet IP address and is behind the Intranet's firewall832. Communications between the pico base station 610 and either the MSS606 or the MG 604 traverse the Intranet's NAT and go over the Internet830 and, therefore, IPSec/SRTP is used to secure such communications andQOS is used to help ensure a desired quality of service.

The various architectures and techniques described above can be used inmany service delivery scenarios. FIG. 11 illustrates one such scenarioin which the technology described here is used to provide wireless localloop (WLL) service for both voice and data within an enterprise (forexample, using low-power RF spectrum) to implement an enterprise mobilenetwork 1100 to provide wireless service within the enterprise. In thisscenario, a MSS 1102 provides MSC, HLR, and PPS services for localmobiles 1104 that are local subscribers to that enterprise mobilenetwork 1100 and provides no roaming for any non-local mobiles thathappen to roam into a coverage area associated with the enterprise.Sessions can be established between a local mobile 1104 and a non-localdevice via the PSTN 1106.

Wireless coverage and capacity is provided by the pico BSS 1108 and DAS1110. A media gateway (MG) 1112 is used to communicatively couple theelements of the enterprise mobile network 1100 to the PSTN 1106 and,under control of the MSS 1102, to switch call media streams betweenmobiles 1104 and devices connected to the PSTN 1106 and to perform anyneeded transcoding. A GPRS Support Node (GSN) 1114 is included in theprivate network 1100 to provide GPRS data service to local mobiles 1104.The GSN 1114 is coupled to the Internet 1116 using a firewall 1118. Theelements of the enterprise mobile network 1100 are communicativelycoupled to one another using the enterprise's IP Intranet 1120.

FIG. 12 illustrates another scenario in which the technology describedhere is used to provide only roaming service within an enterprise. Inthis example, the MSS 1202 implements MSC/VLR functionality to supportsuch roaming. The enterprise mobile network 1200 is used to provideroaming services to other wireless networks and does not itself have anylocal subscribers. In other words, from the perspective of the wirelessoperator's network (PLMN 1222), the MSS 1202 of the enterprise mobilenetwork 1200 appears to be another MSC/VLR of the PLMN 1222. The MSS1202 of the enterprise network 1200 communicates with the other elementsof the PLMN 1222 using the MAP protocol. A media gateway 1224 is used tocommunicatively couple the elements of the enterprise network 1200 tothe PLMN 1222 and, under control of the MSS 1202, to switch call mediastreams between mobiles 1104 and devices connected to the PLMN 1222 andto perform any needed transcoding. Authentication and other functionsare provided by the NSS functionality of the PLMN 1222. Otherwise, theenterprise mobile network 1200 is similar to the enterprise mobilenetwork 1100 of FIG. 11 .

FIG. 13 illustrates another usage scenario in which an enterprise mobilenetwork 1300 is configured to support both local subscribers and“hybrid” subscribers. As used herein, hybrid subscribers are both localsubscribers of the enterprise mobile network 1300 and subscribers of thePLMN 1222. In one implementation, each hybrid subscriber has a localMSISDN that is assigned by the enterprise mobile network 1300 and apublic MSISDN that is assigned by the PLMN 1222. When a hybridsubscriber enters a coverage area associated with enterprise mobilenetwork 1300, a location update is performed with the MSS 1302 of theenterprise mobile network 1300. The local MSS 1302, in connection withsuch a location update, acts as a MSC/VLR for the hybrid subscriber'spublic MSISDN number and communicates with the public HLR (not shown) inthe PLMN 1222 to complete a location update for the hybrid subscriber'spublic MSISDN number using the MAP/D protocol. Also, the local MSS 1302,in connection with such a location update, performs a location updatefor the hybrid subscriber's local MSISDN number and handles both theMSC/VLR and HLR/PPS functions for the location update. As a result, whena hybrid subscriber is within a coverage area associated with theenterprise mobile network 1300, the hybrid subscriber is able to receivecalls made to both its local MSISDN number and its public MSISDN number.When the hybrid subscriber is outside of the coverage area of theenterprise mobile network 1300, the hybrid subscriber is only able toreceive calls made to its public MSISDN number. The MSS 1302 of theenterprise mobile network 1300 also acts as a MSC/VLR to supporthandovers and the like, as well.

FIG. 14 illustrates another usage scenario in which an enterprise mobilenetwork 1400 also includes Private A-link Intelligent Multiplexer(PALIM) switching function 1426 to support three types ofsubscribers—private subscribers (subscribers that are subscribers ofonly the private enterprise mobile network 1400), hybrid subscribers(subscribers that are subscribers of both the private enterprise mobilenetwork 1400 and the public PLMN 1222), and public subscribers(subscribers that are subscribers of the public PLMN 1222 and not asubscriber of the private enterprise mobile network 1400). The PALIMswitching technology 1426 enables the enterprise mobile network 1400 toprovide local NSS functionality for private and hybrid subscribers thatare within a coverage area of the enterprise mobile network 1400 whilesupporting roaming for public subscribers.

The PALIM function 1426 is used to logically couple the rest of theelements of the enterprise mobile network 1400 to the PLMN 1222 usingthe GSM A interface so that the enterprise mobile network 1400 appears,from the perspective of the PLMN 1222, as another base station subsystemof the PLMN 1222 in connection with providing service to publicsubscribers and to hybrid subscribers in connection with their publicMSISDN numbers. However, for local subscribers and hybrid subscribers inconnection with their private MSISDN numbers, the enterprise mobilenetwork 1400 provides full NSS functionality (that is, MSC/VLR andHLR/PSS functions).

FIG. 15 illustrates an example in which an enterprise mobile network1500 is implemented across two offices of an enterprise. In thisexample, two intranets 1520 (in respective offices A and B) arecommunicatively coupled to one another using a virtual private network(VPN) connection (using, for example, the IPSec protocol). In thisexample, the MSS 1402 and GSN 1114 are deployed in Office A, while thePSTN connection and associated MG 1112 is located in Office B. Mobilenetwork traffic is routed among the Intranets 1520 using the underlyingIP network technology.

FIG. 16 illustrates an example in which two separate enterprise mobilenetworks 1600 share a GSN 1614 and MSS 1602. The GSN 1614 and MSS 1602are located in a wireless operator's central office 1628 and areconnected to the respective intranets 1620 of the two enterprises usinga VPN. Mobile network traffic is routed among the Intranets 1620 and theMSS 1602 and GSN 1614 using the underlying IP network technology.

FIG. 17 illustrates an example in which an IP PBX 1730 is integratedwith the enterprise mobile network 1700. In this embodiment, a SIP UserAgent (SIP UA) 1732 included in the MSS 1702 enables wireless mobiledevices 1104 to use the SIP protocol to establish sessions with SIPphones 1734 that are attached to the IP PBX 1730. The IP PBX 1730 iscoupled to the PSTN 1106 via a media gateway 1740.

In this example, the IP PBX 1730 can be configured to associate PBXextension numbers with local subscribers of the enterprise mobilenetwork 1700 (for example, private and hybrid subscribers). For example,where a local subscriber also has a fixed SIP phone 1734 that has aparticular PBX extension number, the IP PBX 1730 and MSS 1702 can beconfigured to associate the same PBX extension number with the localsubscriber's mobile 1104 and calls made to that PBX extension cause boththe SIP phone 1734 and the mobile 1104 to ring. In this way, the mobiledevices 1104 can act as wireless extensions of the IP PBX 1730.

FIG. 18 illustrates an example in which an access gateway 1836 isintegrated with the enterprise mobile network 1800. The access gateway1836 is used to couple SIP devices to other types of voice networks. Inthe particular embodiment shown in FIG. 18 , the access gateway 1836 isused to couple SIP devices to the PSTN 1106 using an analog trunk line1838. In this example, the SIP User Agent 1732 included in the MSS 1702enables the MSS 1702 to use the access gateway 1836 to gain access tothe devices and networks coupled to it (such as the SIP phones 1734 andanalog phones 1840).

FIGS. 19-36 illustrate additional examples of services and usagescenarios that can be implemented using the technology described here.

FIG. 19 illustrates one example of an enterprise mobile network 1900 inwhich the technology described above (for example, a multiple-TRX picobase station and DAS) can be deployed to provide coverage and capacityto GSM/GPRS mobile devices 1902 located within an enterprise 1904. Inthis example, the enterprise mobile network 1900 is not coupled to anyPLMN and is also referred to here as an “isolated” enterprise mobilenetwork 1900. The enterprise 1904 must gain access to suitable GSMspectrum, which is typically licensed spectrum. In this example, one wayin which an enterprise 1904 may access suitable GSM spectrum for use insuch an isolated enterprise mobile network 1900 is to obtain a licenseto use low-power RF spectrum that is available in some jurisdictions.

In this example, a pico base station subsystem 1906 is coupled to a DAS1908. The enterprise mobile network 1900 also comprises a mobileswitching subsystem (MSS) 1910 that is coupled to the pico base stationsubsystem 1906 and is also located in the enterprise 1904. The MSS 1910provides all the NSS related functions for the enterprise mobile network1900. The MSS 1910 is coupled to the PSTN 1912 via an analog PBX 1914.The analog PBX 1914 is also coupled to various analog phones 1916. Amedia gateway 1918 is used provided to perform any needed mediaconversions between the media formats used by the MSS 1910 and pico basestation subsystem 1906 and the media formats used by the analog PBX1914.

The enterprise mobile network 1900 also includes a GSN 1920 that iscoupled to the Internet 1922. The GSN 1920 is used to provide GPRS dataservice to the mobile device 1902 while they are camped on theenterprise mobile network 1900.

In this example, the enterprise mobile network 1900 is configured to beused with the same mobile devices 1902 that the users use when they areoutside of the coverage area of the enterprise mobile network 1900. Thatis, in this example, the mobile devices 1902 (and the associatedsubscriber identity module (SIM) cards) have a home PLMN that is not theenterprise mobile network 1900. The enterprise mobile network 1900 isconfigured to be used with these mobile devices 1902 without requiringthe users to change their subscriber identity module (SIM) cards. If thecoverage area of a user's home PLMN overlaps with the coverage area ofthe enterprise mobile network 1900, the user may need to manually selectthe appropriate network to use.

Each local user of the enterprise mobile network 1900 registers with thenetwork 1900 using the International Mobile Equipment Identity (IMEI)assigned to the user's mobile device 1902 (which the user can accessfrom the mobile device 1902 itself via the device's user interface).Each local user (also referred to here as a “local subscriber”) isassigned a local phone number (local MSISDN) that is used by theenterprise mobile network 1900 to provide wireless cellular service tothat local subscriber. In other words, each such user has a regularpublic mobile phone number that is used in the user's home PLMN and alocal mobile phone number that can be used in the enterprise mobilenetwork 1900.

Also, in this example, each local subscriber has an associated analogphone 1916 that has an associated PBX extension number. In this example,the user can use the call forwarding function provided by the user'shome PLMN to, while the user is not camped onto the home PLMN, forwardcalls that are made to the user's public phone number to the user's PBXextension number. In this example, the PBX 1914 supports a twin ringfeature and is configured so that when a call is made to the user's PBXextension number, the PBX 1914 causes both user's analog fixed phone1916 and mobile phone 1902 (using the user's local mobile phone number)to ring for that call. The PBX 1914 rings the mobile phone 1902 byforwarding the associated signaling and call data to the MSS 1910.

A similar approach can be used with an IP based PBX.

FIG. 20 illustrates another example of an enterprise mobile network 2000in which the technology described above (for example, a multiple-TRXpico base station and DAS) can be deployed to provide coverage andcapacity to GSM/GPRS mobile devices 2002 located within an enterprise2004.

In this example, the enterprise mobile network 2000 gains access to RFspectrum by entering into an agreement with the operator of a PLMN 2006.In this example, the enterprise mobile network 2000 is configured tosupport local subscribers and non-local subscribers (that is, roamers).

A pico base station subsystem 2008 and DAS 2010 is provided within eachoffice of the enterprise 2004. Also, a local MSS 2012 is provided in theenterprise 2004 that is coupled to the pico base station subsystem 2008.The local MSS 2012 is also coupled to a central MSS 2014 located in theoperator's central office 2016. In this example, the local MSS 2012serves as the MSC/VLR for those mobile devices 2002 that are locatedwithin a coverage area associated with the enterprise mobile network2000, and the central MSS 2014 implements the GMSC and HLR functionalityfor all of the offices of the enterprise 2004 and the local subscribersthereof. Each local MSS 2012 is coupled to the central MSS 2014 over anIP Network 2018 using the MAP and ISUP protocols.

The enterprise mobile network 2000 also includes a GSN 2020 that iscoupled to the mobile devices 2002 in each office of the enterprise 2004via the IP network 2018. The GSN 2020 is used to provide GPRS dataservice to the mobile device 2002 while they are camped on theenterprise mobile network 2000. The GSN 2020 is also connected to an IPnetwork 2022 via which the GPRS service is provided. The central office2016 also includes a media gateway (MGW) 2024 that switches calls andperforms any needed media conversion. The central office 2016 alsoincludes a router 2026 for coupling the MSS 2014, GSN 2020, and MGW 2024to the IP network 2018.

Each local MSS 2012 is also coupled to the PSTN 2026 via an analog PBX2028. The analog PBX 2028 is also coupled to various analog phones 2030.A media gateway 2032 is used provided to perform any needed mediaconversions between the media formats used by local MSS 2012 and picobase station subsystem 2008 and the media formats used by the analog PBX2028.

In this example, the HLR in the central MSS 2014 is the HLR for theenterprise's local subscribers and is managed by the operator of thePLMN 2006. As a result, the local subscribers can be registered usingtheir IMSI numbers. The local subscribers are otherwise provided servicein a manner similar to that described above in connection with FIG. 19(including, for example, the integration with PBX 2028).

In this example, the enterprise mobile network 2000 is also used toprovide wireless service to non-local subscribers (including subscribersof the PLMN 2006 and roamers). For such subscribers, the local MSS 2012serves as the MSC/VLR and the roaming service is provided using theroaming arrangements and functionality in the PLMN 2006, which the localMSS 2012 accesses via the IP network 2018.

FIG. 21 illustrates another example of an enterprise mobile network 2100in which the technology described above (for example, a multiple-TRXpico base station and DAS) can be deployed to provide coverage andcapacity to GSM/GPRS mobile devices 2102 located within an enterprise2104.

In this example, base station capacity is deployed within each office ofthe enterprise 2104 and all NSS functions are performed in a PLMN 2106.The enterprise mobile network 2100 does not have local subscribers and,instead, is a part of the PLMN 2106. More specifically, in this example,a pico base station subsystem 2108 and DAS 2110 is provided within eachoffice of the enterprise 2104. Each pico base station subsystem 2108 iscoupled to the NSS functionality of the PLMN 2106 via an IP network2112. For example, as shown in FIG. 21 , a MSS 2114, a GSN 2116, and aMGW 2118 are deployed within a central office 2120 of the operator ofthe PLMN 2106. The MSS 2114, in this example, serves as the MSC/VLR forthe mobile devices 2102 that are within a coverage area associated withthe enterprise 2104.

The GSN 2116 is used to provide GPRS data service to the mobile device2102 while they are camped on the enterprise mobile network 2100. TheGSN 2116 is also connected to an IP network 2122 via which the GPRSservice is provided. The central office 2120 also includes and MGW 2118that switches calls and performs any needed media conversion. Thecentral office 2120 also includes a router 2124 for coupling the MSS2114, GSN 2116, and MGW 2118 to the IP network 2112.

Also, the enterprise mobile network 2100 can be configured to implementvarious types of location based services such as the use of a callrouting table to selectively route calls, Computer SupportedTelecommunications Applications (CSTA)/Call Detail Record (CDR)integration, location based tariffs, virtual HLR/VLR support, localswitching, and distributed mobile station roaming number (MSRN) support.

FIG. 22 illustrates another example of an enterprise mobile network 2200in which the technology described above (for example, a multiple-TRXpico base station and DAS) can be deployed to provide coverage andcapacity to GSM/GPRS mobile devices 2202 located within an enterprise2204.

This example illustrates how the enterprise mobile network 2200 can beintegrated with an IP PBX. In this example, the enterprise mobilenetwork 2200 gains access to RF spectrum by entering into an agreementwith the operator of a PLMN 2206. In this example, enterprise mobilenetwork 2200 is configured to support local subscribers and non-localsubscribers (that is, roamers).

A pico base station subsystem 2208 and DAS 2210 is provided within eachoffice of the enterprise 2204. Also, each pico base station subsystem2208 is coupled to a MSS 2212 located in the operator's central office2214. In this example, the MSS 2212 serves as the MSC/VLR for thosemobile devices 2202 that are located within a coverage area associatedwith the enterprise mobile network 2200. Also, the MSS 2212 implementsthe GMSC and HLR functionality for all of the local subscribers of allof the offices of the enterprise 2202. Each pico base station subsystem2208 is coupled to the MSS 2212 over an IP Network 2216 using an “Aterover IP” interface.

The enterprise mobile network 2200 also includes a GSN 2218 that iscoupled to the mobile devices 2202 in each office of the enterprise 2204via the IP network 2216. The GSN 2218 is used to provide GPRS dataservice to mobile devices 2202 while they are camped on to theenterprise mobile network 2200. The GSN 2218 is also connected to an IPnetwork 2220 via which the GPRS service is provided. The central office2214 also includes a media gateway (MGW) 2222 that switches calls andperforms any needed media conversion. The central office 2214 alsoincludes a router 2224 for coupling the MSS 2212, GSN 2218, and MGW 2222to the IP network 2216.

In this example, the HLR in the MSS 2212 is the HLR for the enterprise'slocal subscribers and is managed by the operator of the PLMN 2206. As aresult, the local subscribers can be registered using their IMSInumbers.

In this example, the enterprise mobile network 2200 is also used toprovide wireless service to non-local subscribers (including subscribersof the PLMN 2206 and roamers). For such subscribers, the MSS 2212 servesas the MSC/VLR and the roaming service is provided using the roamingarrangements and functionality in the PLMN 2206, which the MSS 2212accesses via the IP network 2216.

Each pico base station subsystem 2208 is also coupled to the PSTN 2226via an IP PBX 2228. The IP PBX 2228 is also coupled to various SIPphones 2230. Each pico base station subsystem 2208 is coupled to the IPPBX 2228 via a corporate IP LAN 2232. A SIP session border controller(SBC) 2234, which manages the signaling and media streams for sessionsestablished with mobile devices 2202. In this example, the SBC 2234routes SIP signaling data for such sessions between a SIP User Agent(SIP UA) 2236 in the MSS 2212 and the IP PBX 2228 as needed by routingmedia streams for such sessions among the pico base station subsystem2208 (for ultimate communication with the mobile devices 2202) and theSIP phones 2230. Also, in this example, the SBC 2234 handles transcodingmedia streams communicated between the SIP phones 2230 and the mobiledevices 2202 and any NAT traversals.

As with the example described above in connection with FIG. 19 , in thisexample, the enterprise mobile network 2200 is configured to be usedwith the same mobile devices 2202 that the users use when they areoutside of the coverage area of the enterprise mobile network 2200. Thatis, in this example, the mobile devices 2202 (and the associated SIMcards) have a home PLMN that is not the enterprise mobile network 2200.The enterprise mobile network 2200 is configured to be used with thesemobile devices 2202 without requiring the users to change their SIMcards. If the coverage area of a user's home PLMN overlaps with thecoverage area of the enterprise mobile network 2200, the user may needto manually select the appropriate network to use.

Each local subscriber of the enterprise mobile network 2200 isregistered with the network 2200 and is assigned a local phone number(local MSISDN) that is used by the enterprise mobile network 2200 toprovide wireless cellular service to that local subscriber. In otherwords, each such local subscriber has a regular public mobile phonenumber (also referred to here as the “public MSISDN” or “home MSISDN”)that is used in the user's home PLMN 2206 (and for which the user has anassociated record in the main home HLR in the home PLMN 2206) and alocal mobile phone number that is used in the enterprise mobile network2200 (and for which the user has an associated record in the enterpriseHLR that the MSS 2212 maintains). Also, in this example, each localsubscriber has an associated SIP phone 2230 that has an associated PBXextension number, which is managed by the IP PBX 2228.

As shown in FIG. 23 , when a local subscriber moves into a coverage areaassociated with the enterprise mobile network 2200, the localsubscriber's mobile device 2202 performs a location update with the MSS2212. This location update is forwarded from the pico base stationsubsystem 2208 to the MSS 2212 over the IP Network 2216. The MSS 2212,acting as an MSC/VLR, handles the location update in the normal mannerto update the local subscriber's information in the home HLR in the homePLMN 2206 with respect to the local subscriber's home MSISDN number.This enables the local subscriber to receive calls made to thesubscriber's home MSISDN number while the local subscriber is campedonto the enterprise mobile network 2200. In this example, thesubscriber's local MSISDN number is registered with the enterprise HLRthat the MSS 2212 maintains. Also, the SIP UA 2236 in the MSS 2212registers with the IP PBX 2228 so that the IP PBX 2228 will contact itwhen calls are made to the local subscriber's PBX extension using thetwin ring feature of the IP PBX 2228.

FIG. 24 illustrates how a mobile device 2202 that is camped onto theenterprise mobile network 2200 can make a call to a device connected tothe PSTN 2206. As shown in FIG. 24 , when the mobile device 2202 callssuch an external device, the signaling data for the mobile originated(MO) leg of the call is communicated to the MSS 2212. In this example,there are two options for completing the call. In the first option, theMSS 2212 is configured to set-up the call using the IP PBX 2228. This isdone by having the SIP UA 2236 in the MSS 2212 make the call using IPPBX 2228. In other words, the SIP UA 2236 appears to be another SIPPhone 2230 that is making a call. Once the call is setup, the mediastreams for the MO leg of the call are routed between the mobile device2202 and the IP PBX 2228 using the corporate LAN 2232 and the SBC 2234,where the SBC 2234 performs any needed media conversions between themedia formats used by mobile device 2202 and the format used by the IPPBX 2228 and the IP PBX 2228 performs any needed media conversionsbetween the format used by the IP PBX 2228 and format used by the PSTN2226. In the second option, the MSS 2212 is configured to set-up thecall using the PLMN 2206 like any other GSM call. Once the call issetup, the media streams for the MO leg of the call are routed betweenthe mobile device 2202 and the PLMN 2206 using the MGW 2222, whichperforms any needed media conversions. With both options, the pico basestation subsystem 2208 is used to provide the radio link to the mobiledevice 2202.

FIG. 25 illustrates how a call that is made to a MSISDN numberassociated with a local subscriber (for example, the subscriber's localMSISDN or public home MSISDN) can be completed using the enterprisemobile network 2200 of FIG. 22 . When a local subscriber is camped ontothe enterprise mobile network 2200 and a call is made to a MSISDN numberassociated with that local subscriber, the PLMN 2206 will route thesignaling associated with the call to the MSS 2212. The MSS 2212 acts asthe MSC/VLR for the PLMN 2206 and will cause the local subscriber'smobile device 2202 to ring by sending appropriate signaling messages tothe mobile device 2202 using the pico base station subsystem 2208. Ifthe local subscriber uses the mobile device 2202 to answer the call, theMSS 2212 sets up the media streams for the call in the conventional GSMmanner using the pico base station subsystem 2208 and MGW 2222. The MSS2212 will also cause the SIP phone 2230 associated with that localsubscriber to ring as well. The MSS 2212 does this by having the SIP UA2230 setup a call with the IP PBX 2228 that is addressed to the localsubscriber's associated PBX extension. The IP PBX 2228 will ring the SIPphone 2230 associated with that PBX extension. If the local subscriberuses the SIP phone 2230 to answer the call, the MSS 2212 sets up mediastreams for the call between the PLMN 2206 (and the calling phone) andthe SIP phone 2230 using the MGW 2222 (which performs any needed mediaconversions between the media formats used by the SIP phone 2230 (forexample, the RTP format) and the GSM media formats used in the PLMN2206).

FIG. 26 illustrates how a call that is made to a PBX extension numberassociated with a local subscriber can be completed in using theenterprise mobile network 2200 of FIG. 22 . When a local subscriber iscamped onto the enterprise mobile network 2200 and a call is made to aPBX extension associated with that local subscriber, the PSTN 2226 willroute the signaling associated with such a call to the IP PBX 2228. TheIP PBX 2228, in the conventional manner, will cause the localsubscriber's SIP phone 2230 to ring by sending appropriate signalingmessages to the SIP phone 2230. If the local subscriber uses the SIPphone 2230 to answer the call, the IP PBX 2228 sets up the media streamsfor the call in the conventional manner between the IP PBX 2228 and theSIP phone 2230. In this example, the IP BPX 2228 will also cause themobile device 2202 associated with that local subscriber to ring as well(using the twin ring feature of the IP PBX 2228). The IP PBX 2228 doesthis by interacting with the SIP UA 2236 in the MSS 2212 as if the SIPUA 2236 was another SIP Phone. In response to this, the SIP UA 2236causes the mobile device 2202 to ring using the pico base stationsubsystem 2208. If the local subscriber uses the mobile device 2202 toanswer the call, the MSS 2212 sets up the call between the mobile device2202 and the IP PBX 2228. Once the call is setup, the media streams forthe call are routed between the mobile device 2202 and the IP PBX 2228using the corporate LAN 2232 and the SBC 2234, where the SBC 2234performs any needed media conversions between the media formats used bymobile device 2202 and the format used by the IP PBX 2228 and the IP PBX2228 performs any needed media conversions between the format used bythe IP PBX 2228 and the format used by the PSTN 2226.

FIG. 27 illustrates another example of an enterprise mobile network 2700in which the technology described above (for example, a multiple-TRXpico base station and DAS) can be deployed to provide coverage andcapacity to GSM/GPRS mobile devices 2702 located within an enterprise2704.

In this example, a pico base station subsystem 2706 is coupled to a DAS2708. The enterprise mobile network 2700 also comprises a mobileswitching subsystem (MSS) 2710 that is coupled to the pico base stationsubsystem 2706 and is also located in the enterprise 2704. In thisexample, the enterprise mobile network 2700 is coupled to a PLMN 2718with which the enterprise 2704 has an agreement. In this example, thelocal subscribers of the enterprise 2704 have both a local MSISDNnumbers and a public MSISDN number as described above, and the MSS 2710acts as the HLR (as well as the MSC/VLR) for the local subscribers withrespect to their local MSISDN numbers but only acts as an MSC/VLR forthe local subscribers with respect to their public MSISDN numbers.

In the example shown in FIG. 27 , the MSS 2710 is also coupled to thePSTN 2712 via an IP PBX 2714. The MSS 2710 is coupled to the IP PBX 2714via a corporate LAN and session border controller (both of which are notshown in FIG. 27 ). The IP PBX 2714 is also coupled to various SIPphones 2716. Any needed transcoding between the media formats used bythe pico base station subsystem 2706 and those used by the IP PBX 2714can be performed by the SBC and/or the IP PBX 274 itself.

The enterprise mobile network 2700 also includes a GSN 2720 that iscoupled to the Internet 2722. The GSN 2720 is used to provide GPRS dataservice to the mobile device 2702 while they are camped on theenterprise mobile network 2700.

In this example, the enterprise 2704 has also deployed unifiedcommunications (UC) technology. The UC technology is implemented in theenterprise 2704 using one or more UC servers 2724 that arecommunicatively coupled to various UC end points 2726 (such as personalcomputers, telephones, and video conferencing equipment) and other IPdevices (such as the SIP phones 2716 and the IP PBX 2714) using thecorporate IP LAN. In particular, the UC servers 2724 integrate andmanage real-time, synchronous communication services (such as VOIPtelephony, instant messaging, audio and video conferencing, and privatecellular telephony) and asynchronous communication services and unifiedmessaging (such as asynchronous communication services like email, voicemail, faxes, calendaring, and presence) in order to, among other things,provide unified messaging to users' “inboxes”. In one implementation ofsuch an embodiment, the UC servers 2724 are implemented using MicrosoftOffice Communications Server 2007 to integrate and manage synchronouscommunication services and Microsoft Exchange Server 2007 to integrateand manage asynchronous communication services and to deliver unifiedmessaging. In such an implementation, the UC server software is hostedlocally within the enterprise 2704 (that is, the UC server softwareexecutes on server hardware that is deployed in the enterprise 2704).Although the UC servers 2724 are shown in FIG. 27 as being deployedwithin the enterprise 2704, it is to be understood that in otherembodiments the UC servers 2724 include one or more UC servers orservices that are provided by outside service providers (also referredto as “hosted” services), such as hosted Microsoft Exchange Serverservices or Microsoft Office Communications Server services).

In this example, various UC end points 2726 run UC client software thatis compatible with the UC servers 2724 (such as Microsoft OfficeCommunicator 2007 for synchronous communication service and/or MicrosoftOutlook 2007 for asynchronous communication service and to access theuser's unified messaging inbox). Also, the UC server 2724 that managessynchronous communication services integrates the IP PBX 2714 and theSIP phones 2716 into the overall UC solution. The MSS 2710 includes SIPUser Agent (UA) (not shown in FIGS. 27-31 ) that the MSS 2710 uses tointeract with the IP PBX 2714 and the UC server 2724. In this way, themobile devices 2702 appear to the IP PBX 2714 and UC 2714 to be anotherSIP device.

The UC technology can be used to unify each local subscriber's mobiledevice 2702, fixed SIP phone 2716, and other UC end points 2726 withrespect to synchronous and asynchronous communications. For example, asshown in FIG. 28 , when a telephone call is made to a PBX extensionassociated with a local subscriber of the enterprise 2704, the call willbe received at the IP PBX 2714 from the PSTN 2712. The IP PBX 2714 isconfigured to ring the SIP phone 2716 of the called user in the normalmanner. Also, the IP PBX 2714 is configured to interact with the SIP UAin the MSS 2710 in order to cause the called user's mobile device 2702to ring (if the mobile device 2702 is camped onto the enterprise mobilenetwork 2700 at that time). As noted above, the SIP UA in the MSS 2710appears to be, from the perspective of the IP PBX 2714, another SIPdevice.

The IP PBX 2714 is also configured to interact with the UC server 2724that handles synchronous communication services to indicate that thereis an incoming call for the called user. The UC server 2724 causes thecalled user's UC end point 2726 to ring or otherwise indicate that anincoming call is being attempted.

If the called local subscriber uses the fixed SIP phone 2716 to answerthe call, the IP PBX 2714 sets ups the media streams for the call in theconventional manner between the IP PBX 2714 and the fixed SIP phone2716. If the user uses the UC end point 2726 to answer the call, the UCserver 2724 and the IP PBX 2714 set up the call.

If the user uses the mobile device 2702 to answer the call, the IP PBX2714 sets up the call with the SIP UA in the MSS 2710, and the MSS 2710in turn sets up the call with the called user's mobile device 2702 (viathe pico base station subsystem 2706 and DAS 2708). Once the call issetup, the media streams for the call are routed between the calledmobile device 2702 and the calling device connected to the PSTN 2712(where any needed transcoding can be performed by a SBC that is used tocouple the pico base station subsystem 2706 to the corporate IP LAN andthe IP PBX 2714).

FIG. 29 illustrates an example in which someone uses a fixed SIP phone2716 to call a user's PBX extension. The processing of such call issubstantially similar to the processing described above in connectionwith FIG. 28 .

FIG. 30 illustrates an example in which someone uses a mobile device2702 to call a user's local MSISDN number. The MSS 2710 is configured toring the called local subscriber's mobile device 2702 in the normalmanner. Also, the MSS 2710 uses the SIP UA to call both the IP PBX 2714and the UC server 2724 that handles synchronous communication services.The IP PBX 2714 and the UC server 2724 cause the called user's fixed SIPphone 2716 and UC end point 2726, respectively, to ring or otherwiseindicate that an incoming call is being attempted.

If the user uses the mobile device 2702 to answer the call, the MSS 2710sets up the call in the normal manner.

If the local subscriber uses the fixed SIP phone 2716 to answer thecall, the IP PBX 2714 sets up the call with the SIP UA in the MSS 2710,and the MSS 2710 in turn sets up the call with the calling user's mobiledevice 2702 (via the pico base station subsystem 2706 and DAS 2708).Once the call is setup, the media streams for the call are routedbetween the called mobile device 2702 and the calling fixed SIP phone2716 (where any needed transcoding can be performed by a SBC that isused to couple the pico base station subsystem 2706 to the corporate IPLAN).

If the called user uses the UC end point 2726 to answer the call, the UCserver 2724 sets up the call with the SIP UA in the MSS 2710, and theMSS 2710 in turn sets up the call with the calling user's mobile device2702 (via the pico base station subsystem 2706 and DAS 2708). Once thecall is setup, the media streams for the call are routed between thecalling mobile device 2702 and the called UC end point 2726 (where anyneeded transcoding can be performed by a SBC that is used to couple thepico base station subsystem 2706 to the corporate IP LAN).

FIG. 31 illustrates an example in which someone uses a UC end point 2726(such as a computer) to call a user's UC end point 2726. The UC server2724 that handles synchronous communications is configured to ring thecalled user's UC end point 2726 (or otherwise indicate at the calleduser's UC end point 2726 that an incoming call is being attempted) inthe normal manner. Also, the UC server 2724 causes the called user'sfixed SIP phone 2716 to ring using the IP PBX 2714 in the normal manner.In this example, the UC server 2724 is also configured to interact withthe SIP UA in the MSS 2710 in order to cause the called user's mobiledevice 2702 to ring (if the mobile device 2702 is camped onto theenterprise mobile network 2700 at that time). As noted, the SIP UA inthe MSS 2710 appears to be, from the perspective of the UC server 2724,another SIP device.

If the called user uses the UC end point 2726 to answer the call, the UCserver 2724 sets up the call between the calling UC end point 2726 andthe called UC end point 2726 in the normal manner. Likewise, if thecalled user uses the fixed SIP phone 2716 to answer call, the UC server2724 and the IP PBX 2714 set up the call with the fixed SIP phone 2716in the normal manner.

If the user uses the mobile device 2702 to answer the call, the UCserver 2724 sets up the call with the SIP UA in the MSS 2710, and theMSS 2710 in turn sets up the call with the called user's mobile device2702 (via the pico base station subsystem 2706 and DAS 2708). Once thecall is setup, the media streams for the call are routed between thecalled mobile device 2702 and the calling UC server 2724 (where anyneeded transcoding can be performed by a SBC that is used to couple thepico base station subsystem 2706 to the corporate IP LAN).

FIG. 32 illustrates an example in which a computer/telephone integration(CTI) application 3202 installed on the UC end point 2726 is used toremotely control the user's mobile device 2702. In this example, the MSS2710 includes a Computer Supported Telecommunications Applications(CSTA)/SIP interface 3204 that is used to interact with CTI applicationsthat may be executing on the UC end points 2726. In this example, theCTI application 3202 is designed to remotely control the user's mobiledevice 2702. For example, the UC technology may include a so called“click to call” function, whereby a user can click on some part of theuser interface of the UC end point 2726 in order to initiate a call.This click-to-call function can be extended to initiate a call using theuser's mobile device 2702. When the user make's such a click, the CTIapplication 3202 interacts with the CSTA/SIP interface 3204 in the MSS2710 indicating the MSS 2710 should initiate an mobile originated (MO)call from the mobile device 2702, which the MSS 2710 proceeds to do ifthe user's mobile device 2702 is camped onto the enterprise mobilenetwork 2702. If the call is answered, the MSS 2710 sets up the callwith the mobile device 2702 and the called party as if the user used themobile device 2702 to make the call.

In the examples described above in connection with FIGS. 27-32 , the MSS2710 can be configured to provide presence information to the UC server2724 about the mobile device 2702 for use by the UC servers 2724 (forexample, to display presence information about the mobile devices 2702in an UC client (such as Microsoft Office Communicator 2007) executingon the UC end points 2726).

FIG. 33 illustrates another example deployment of an enterprise mobilenetwork 3300 in which the technology described above (for example, amultiple-TRX pico base station and DAS) can be deployed to providecoverage and capacity to GSM/GPRS mobile devices 3302 located within anenterprise 3304.

The example shown in FIG. 33 is similar to the one shown in FIG. 22except that there is no IP PBX deployed locally within one or more ofthe offices of the enterprise 3304. As with the example shown in FIG. 22, the enterprise mobile network 3300 shown in FIG. 33 includes a picobase station subsystem 3308 and DAS 3310 are provided within each officeof the enterprise 3304. Also, each pico base station subsystem 3308 iscoupled to a MSS 3312 located in the operator's central office 3314. Inthis example, the MSS 3312 serves as the MSC/VLR for those mobiledevices 3302 that are located within a coverage area associated with theenterprise mobile network 3300. Also, the MSS 3312 implements the GMSCand HLR functionality for the local subscribers of all of the offices ofthe enterprise 3300. Each pico base station subsystem 3308 is coupled tothe MSS 3312 over an IP Network 3316.

As with the example shown in FIG. 22 , the enterprise mobile network3300 shown in FIG. 33 includes a GSN 3318 that is coupled to the mobiledevices 3302 in each office of the enterprise 3304 via the IP network3316. The GSN 3318 is used to provide GPRS data service to the mobiledevice 3302 while they are camped on to the enterprise mobile network3300. The GSN 3318 is also connected to an IP network 3320 via which theGPRS service is provided. The central office 3314 also includes a mediagateway (MGW) 3322 that switches calls and performs any needed mediaconversion. The central office 3314 also includes a router 3324 forcoupling the MSS 3312, GSN 3318, and MGW 3322 to the IP network 3316.

As noted above, in the example shown in FIG. 33 , there is no IP PBXdeployed locally within the offices of the enterprise 3304. Instead,virtual IP PBX software 3328 executes on the MSS 3312 so that the MSS3312 can act as a PBX for the enterprise 3300 for both the mobiledevices 3302 and any other SIP devices (such as fixed SIP telephones3330). The virtual IP PBX software 3328 and the SIP devices communicatewith one another over the IP Network 3316 using the SIP protocol forsignaling and a suitable media format (such as the Real-time TransportProtocol (RTP)) for the call data. The virtual IP PBX 3328 is alsoconfigured to associate a PBX extension number with a respective fixedSIP telephone 3330 so that calls made to that PBX extension number willcause the associated fixed SIP telephone 3330 to ring.

In this example, each office of the enterprise 3304 includes an accessgateway 3350 that is controlled by the virtual IP PBX software 3328 (forexample, using the Media Gateway Control Protocol (MGCP)). The accessgateway 3350 serves as a local gateway to the PSTN 3326 so that calldata sent to or from SIP phones 3330 or the mobile devices 3302 can becommunicated to the PSTN 3326 without having to pass through the MSS3312 and the PLMN 3306. The access gateway 3350 is coupled to the SIPphones 3330 and the pico base station subsystem 3308 via a corporate IPLAN (not shown in FIG. 33 ). The access gateway 3350 performs any neededmedia conversion between the media formats used in the enterprise mobilenetwork 3300 and the formats used in the PSTN 3326). The virtual IP PBXsoftware 3328 (and the devices coupled thereto) can also accesses thePSTN 3326 via the PLMN 3306.

The virtual IP PBX software 3328 is used to provide Centrex-likeservices that wireless telephony providers have historically providedfor fixed wireline telephones. The virtual IP PBX software 3328executing on the MSS 3312 implements Centrex-type features such as shortnumber dialing, outgoing calls using a special leading digit (forexample, the number “9”), and outgoing call barring. The virtual IP PBXsoftware 3328 can also be coupled to a voice mail server to providevoice mail service for user's of the enterprise mobile network 3300.

As with the local IP PBX shown in FIG. 22 , the central virtual IP PBXsoftware 3328 of FIG. 33 is configured to ring both the fixed SIPtelephone 3330 and the mobile device 3302 associated with a given localsubscriber when an incoming call is made to a number associated witheither of those devices.

In the above examples, a public IP network such as the Internet is usedto communicatively couple the pico base station subsystem (and any MSSdeployed within the enterprise) to wireless operator's equipment. As aresult, the IP traffic carrying the signaling and call data needs to besecured. FIG. 34 illustrates one approach to securing such IP traffic.As shown in FIG. 34 , security gateway (SEG) functionality 3450 isdeployed at the pico base station subsystem 3406, a router 3410 used tocouple elements deployed with in the enterprise 3400 to a public IPnetwork 3418, the router 3426 used to couple the elements deployed atthe wireless operator's office 3416 to the public IP network 3418, atthe MSS 3412 deployed in the wireless operator's office 3416, and at themedia gateway (MGW) 3422 deployed in the wireless operator's office3416.

In this example, the IP traffic that passes between the enterprise 3404and the wireless operator's office 3416 is secured using the InternetProtocol Security (IPSEC) protocol. The SEG functionality 3450 supportsthe IPSEC protocol and is used to implement a virtual private networkover which such IP traffic can be communicated in a secure manner, whereSEG functionality 3450 is used at each end of each VPN channel. In thisexample, the devices in the network 3400 use the Secure RTP (SRTP)protocol to further secure the media streams that are communicated overthe public IP network 3418, while signaling data (for example,Ater-over-IP data, Gb-over-IP data, and/or SIP data) is secured usingthe underlying IPSEC channel.

The SEG functionality 3450 can be integrated into the relevant networkelement (for example, in the pico base station subsystem 3406 or the MSS3412 (if there is sufficient processing capability to do so) and/or inthe routers 3410 and 3426 and the media gateway 3422) or provided by aseparate device deployed with the relevant network element where therelevant network element does not have sufficient processing capabilityto implement the SEG functionality 3450 (for example, by deploying aCISCO router supporting the relevant security functions where the MSS3412 does not have sufficient processing capability to itself implementthe SEG functionality 3450).

Also, in the example described here, a SIP user agent is deployed in theMSS in order to couple the mobile network elements to SIP-based networkelements (including SIP servers such as an IP PBX or UC server).However, it is to be understood that fixed-mobile convergence (FMC) canbe implemented in other ways. For example, the mobile devices themselvescan execute a SIP client to act as a peer in such SIP systems (asdefined in the 3GPP/IMS specifications) using a packet-switched corenetwork. However, where the enterprise mobile network is not able tosupport such an approach (for example, because the enterprise mobilenetwork does not implement UMTS), other approaches can be used. Forexample, SIP-server functionality can be integrated into the MSS, a SIPuser agent can be deployed in the MSS, or a SIP user agent can bedeployed in the base station subsystem.

FIG. 35 illustrates how SIP-server functionality can be integrated intoan MSS 3500 as a part of a FMC solution. As shown in FIG. 35 , the MSC(switching) functionality 3502 of the MSS 3500 is extended to supportthe SIP Proxy function 3504, SIP Redirect function 3506, and SIPRegistrar function 3508. The VLR 3510 of the MSS 3500 is enhanced tosupport the SIP Location function 3512. The HLR 3514 of the MSS 3500 isextended to store each subscriber's SIP Profile 3516 with the GSMsubscription information. The authentication center (AUC) 3518 in theMSS 3500 is extended to support the SIP Authentication algorithms 3520.

In this example, the MSS 3500 can be used to support SIP devices and SIPservers such as SIP phones and an IP PBX. The MSS 3500 can also beconfigured to provide GSM services to SIP phones. Examples of such GSMservices include basic call support, mobility management, supplementaryservices, prepaid services, call data record (CDR)/call statistics,voice announcements, and voice mail.

As discussed above in connection with FIGS. 22-26 , the SIP User Agentcan be implemented in the MSS.

FIG. 36 illustrates how a SIP User Agent can be implemented in a basestation subsystem. The example shown in FIG. 36 is implemented in amodified version of the enterprise mobile network 2200 described abovein connection with FIGS. 22-26 .

In the example shown in FIG. 36 , the SIP User Agent (SIP UA) 3650 isimplemented in a pico base station subsystem 3608, instead of in a MSS3612.

When a local subscriber's mobile device 2202 performs a location update,the SIP UA 3650 in the pico base station subsystem 3608 registers thelocal subscriber with the IP PBX 2228. The SIP UA 3650, from theperspective of the IP PBX 2228, appears to be another, normal SIPdevice.

When a user uses a SIP phone 2230 to call the PBX extension of a localsubscriber of the enterprise mobile network 2200, the IP PBX 2228 causesthe fixed SIP phone 2230 associated with the called PBX extension toring. In this example, the IP PBX 2228 is also configured to interactwith the SIP UA 3650 in order to ring the called party's mobile device2202. From the perspective of the IP PBX 2228, the SIP UA 3650 in thepico base station subsystem 3608 appears to be a normal SIP device andthe IP PBX 2228 uses standard SIP signaling to let the SIP UA 3650 knowthat an incoming call has been received for the called party. The SIP UA3650, in turn, generates appropriate GSM signaling messages from the SIPmessages received from the IP PBX 2228 and generates appropriate SIPmessages from GSM signaling messages it receives from the mobile device2202 (via the pico base station subsystem 3608). If the user uses themobile device 2202 to answer the incoming call, the IP PBX 2228 sets upthe call with the SIP UA in the pico base station subsystem 3608, andthe pico base station subsystem 3608 in turn sets up the call with thecalled party's mobile device 2202 (via the pico base station subsystem3608 and DAS 2208). Once the call is set up, the media streams for thecall are routed between the called mobile device 2202 and the callingSIP Phone 2230 (where any needed transcoding can be performed by a SBCused to couple pico base station subsystem 3608 to the corporate IP LAN2232).

The methods and techniques described here may be implemented in digitalelectronic circuitry, or with a programmable processor (for example, aspecial-purpose processor or a general-purpose processor such as acomputer) firmware, software, or in combinations of them. Apparatusembodying these techniques may include appropriate input and outputdevices, a programmable processor, and a storage medium tangiblyembodying program instructions for execution by the programmableprocessor. A process embodying these techniques may be performed by aprogrammable processor executing a program of instructions to performdesired functions by operating on input data and generating appropriateoutput. The techniques may advantageously be implemented in one or moreprograms that are executable on a programmable system including at leastone programmable processor coupled to receive data and instructionsfrom, and to transmit data and instructions to, a data storage system,at least one input device, and at least one output device. Generally, aprocessor will receive instructions and data from a read-only memoryand/or a random access memory. Storage devices suitable for tangiblyembodying computer program instructions and data include all forms ofnon-volatile memory, including by way of example semiconductor memorydevices, such as EPROM, EEPROM, and flash memory devices; magnetic diskssuch as internal hard disks and removable disks; magneto-optical disks;and DVD disks. Any of the foregoing may be supplemented by, orincorporated in, specially-designed application-specific integratedcircuits (ASICs).

A number of embodiments of the invention defined by the following claimshave been described. Nevertheless, it will be understood that variousmodifications to the described embodiments may be made without departingfrom the spirit and scope of the claimed invention. Accordingly, otherembodiments are within the scope of the following claims.

What is claimed is:
 1. A system for providing wireless coverage andcapacity for a at least one public land mobile network within abuilding, the system comprising: a pico base station comprising multipletransceiver units, wherein the pico base station is installed in thebuilding; and a plurality of antennas located within the building,wherein the plurality of antennas are located remotely from the picobase station; a distributed antenna system to couple the pico basestation to the plurality of antennas, wherein the distributed antennasystem comprises a hub unit installed within a rack and a plurality ofremote antenna units located within the building, wherein the hub unitof the distributed antenna system is a separate component than the picobase station, wherein the remote antenna units are located remotely fromthe hub unit and each of the plurality of antennas is coupled to atleast one of the plurality of remote antenna units; wherein the picobase station is communicatively coupled to the at least one public landmobile network, where each transceiver unit of the multiple transceiverunits of the pico base station is coupled to the hub unit of thedistributed antenna system; wherein the pico base station iscommunicatively coupled to the plurality of antennas; wherein the picobase station is configured so that the to output wireless traffic isoutput by the pico base station at a power level less than one Watt;wherein the system further comprises a distributed antenna system tocouple the pico base station to the plurality of antennas; and whereinthe distributed antenna system comprises a hub unit installed within arack included in the server room and a plurality of remote antenna unitslocated within the building, wherein the remote antenna units arelocated remotely from the hub unit and each of the plurality of antennasis coupled to at least one of the plurality of remote antenna units.wherein the hub unit includes one or more converters configured toconvert the wireless traffic output by the pico base station to a firstform, wherein each of the remote antenna units includes one or moreconverters configured to convert the wireless traffic from the firstform to a second form, wherein the wireless traffic is radiated from theantennas in the second form.
 2. The system of claim 1, wherein thebuilding is not controlled by a person or entity other than a serviceprovider associated with the at least one public land mobile network. 3.The system of claim 1, wherein the hub unit is communicatively coupledto the remote antenna units, at least in part, using at least one ofunshielded twisted pair cabling, cable television cabling, opticalfiber, and coaxial cabling.
 4. The system of claim 1, wherein the hubunit and at least one of the plurality of remote antenna units arecommunicatively coupled to one another via an expansion hub.
 5. Thesystem of claim 4, wherein the expansion hub is communicatively coupledto the remote antenna units, at least in part, using at least one ofunshielded twisted pair cabling, cable television cabling, opticalfiber, and coaxial cabling.
 6. The system of claim 1, wherein the picobase station unit is communicatively coupled to the at least one publicland mobile network using an Internet Protocol (IP) backhaul connectionfor which voice signals are converted to IP packets.
 7. The system ofclaim 1, wherein the pico base station further comprises one or morecircuits configured to: base station controller functionalitycontrol themultiple transceiver units and enable the multiple transceiver units tocommunicate with the at least one public land mobile network; andnetwork switching subsystem functionalityperform at least a portion ofcall switching normally implemented in a mobile switching center.
 8. Thesystem of claim 1, wherein the pico base station further comprises aSession Initiation Protocol (SIP) agent to establish sessions withdevices that support the SIP protocol.
 9. A pico base station systemcomprising: a pico base station that includes:an enclosure; a pluralityof radio transceivers, housed within the enclosure, to transmit andreceive, within a building, wireless traffic using radio frequencyspectrum assigned to a at least one public land mobile network; and aninterface to communicatively couple the plurality of radio transceiversto the at least one public land mobile network using an InternetProtocol (IP) backhaul connection for which voice signals are convertedto IP packets; wherein the pico base station is configured so that tooutput the wireless traffic is output by the pico base station at apower level less than one Watt; wherein the pico base station is coupledto a distributed antenna system used to couple the pico base station toa plurality of antennas; and wherein thea distributed antenna systemcomprisesincluding a hub unit installed within a rack included in aserver room and a plurality of remote antenna units located within a thebuilding, wherein the hub unit is a separate component than the picobase station, wherein the remote antenna units are located remotely fromthe hub unit and each of the plurality of antennas is coupled to atleast one of the plurality of remote antenna units, wherein each radiotransceiver of the plurality of radio transceivers of the pico basestation is configured to be coupled to a hub unit of the distributedantenna system used to couple the pico base station to a plurality ofantennas; wherein the hub unit includes one or more convertersconfigured to convert the wireless traffic output by the pico basestation to a first form, wherein each of the remote antenna unitsincludes one or more converters configured to convert the wirelesstraffic from the first form to a second form, wherein the wirelesstraffic is radiated from the antennas in the second form.
 10. The picobase station system of claim 9, wherein the enclosure has arack-mountable shape.
 11. The pico base station system of claim 9,further comprising base station controller functionality one or morecircuits communicatively coupled to the plurality of radio transceivers,wherein the one or more circuits are configured to perform at least somebase station controller operations for the plurality of radiotransceivers.
 12. The pico base station system of claim 9, furthercomprising one or more circuits configured to: base station controllerfunctionalitycontrol the multiple transceiver units and to enable themultiple transceiver units to communicate with the at least one publicland mobile network; and network switching subsystemfunctionalityperform at least a portion of call switching normallyimplemented in a mobile switching center.
 13. An enterprise networkproviding wireless coverage and capacity for a at least one public landmobile network within a building located on a premises of an enterprise,the system enterprise network comprising: a pico base station comprisingmultiple transceiver units, wherein the pico base station is installedin the building and is configured to communicate using licensed radiofrequency spectrum; a plurality of antennas located within the building,wherein the plurality of antennas are located remotely from the picobase station; and a distributed antenna system to communicatively couplethe pico base station to the plurality of antennas, wherein thedistributed antenna system comprises a hub unit installed within a rackand a plurality of remote antenna units located within the building,wherein the hub unit is a separate component than the pico base station,wherein the remote antenna units are located remotely from the hub unitand each of the plurality of antennas are coupled to at least one of theplurality of remote antenna units; and wherein the pico base station iscommunicatively coupled to the at least one public land mobile network,wherein each transceiver unit of the multiple transceiver units of thepico base station is coupled to the hub unit of the distributed antennasystem; wherein the pico base station further comprises one or morecircuits configured to: base station controller functionalityto controlthe multiple transceiver units and to enable the multiple transceiverunits to communicate with the at least one public land mobile network;and network switching subsystem functionalityperform at least a portionof call switching normally implemented in a mobile switching center; andwherein the distributed antenna system comprises a hub unit installedwithin a rack included in a server room and a plurality of remoteantenna units located within the building, wherein the remote antennaunits are located remotely from the hub unit and each of the pluralityof antennas are coupled to at least one of the plurality of remoteantenna units; and wherein the pica pico base station is configured sothat the to output wireless traffic is output by the pico base stationat a power level less than one Watt.
 14. The system enterprise networkof claim 13, wherein the building is not controlled by a person orentity other than a service provider associated with the at least onepublic land mobile network.
 15. The system enterprise network of claim13, wherein the hub unit is communicatively coupled to the remoteantenna units, at least in part, using at least one of unshieldedtwisted pair cabling, cable television cabling, optical fiber, andcoaxial cabling.
 16. The system enterprise network of claim 13, whereinthe hub unit and at least one of the plurality of remote antenna unitsare communicatively coupled to one another via an expansion hub.
 17. Thesystem enterprise network of claim 16, wherein the expansion hub iscommunicatively coupled to the remote antenna units, at least in part,using at least one of unshielded twisted pair cabling, cable televisioncabling, optical fiber, and coaxial cabling.
 18. The system enterprisenetwork of claim 13, wherein the pico base station unit iscommunicatively coupled to the at least one public land mobile networkusing an Internet Protocol (IP) backhaul connection for which voicesignals are converted to IP packets.
 19. The system enterprise networkof claim 13, wherein the network switching subsystem functionalitycomprises one or more circuits are configured to perform at least aportion of call switching normally implemented in a mobile switchingcenter using a private mobile switching center server and a private homelocation register for providing wireless service to local subscribers ofthe enterprise using the licensed radio frequency in connection withlocal mobile phone numbers.
 20. The system of claim 13, wherein the picobase station further comprises a Session Initiation Protocol (SIP) agentto establish sessions with devices that support the SIP protocol. 21.The system of claim 1, wherein the pico base station and the hub unitare housed within a common chassis.
 22. The enterprise network of claim13, wherein the pico base station and the hub unit are housed within thesame chassis.